Manufacture of reenforced concrete



Pateritecl Sept. 18, 1928.

3.10mi) E. DILL, or ALEXANDRIA, NEBRASKA.

' Marianne runs or REENFOROED con-cams.

Application filed February 7, 1925. Serial No. 7,718.

- 'Fhis applicationis filed as a continuation 1n part of my prior, application Serial Number 618,733, filed February'12, 192 3, manufacture of reenforced concrete.

The present invention relates generally to the manufacture o reenforced concrete. Its object is to produce a manufacture of reenforced concrete-that recognizes the difference in qualities of concrete and steel and combines the two materials in a scientific manner. Specifically, it is the object of my lnvention to provide a mobile relation between the concrete. and the reenforcing material and to provide means for subjecting the reenforclng material to tension.

Having in View these objects and others which will be pointed out in the following description, I will now refer to the drawings,

which are illustrative of the methods which I employ, and in which V Figure 1 is a view in crete beam with a portion broken away to disclose the reenforcing and showing the construction whereby the reenforcing may be tensioned. F igure-2 is a view of trally positioned reenforcing and means for tensioning-the reenforcement.

Figure'Q is a transverse sectlonal view of the lamp post shown in'Figure 2.

Figure 3 is a PBISPQCtlVQVlQW of a post or pillar with the lower end of the reenforce embedded and anchored in the concrete.

Figure3 is'a fragmentary sectional view of the'upper portion of the post shown 1n Figure 3. r Figure 4 is a perspective view, partly in section, of-the up er portion of a chimney, showing the man or in jVlllCh the concrete to walls are reenforced. I

' Figure 4 is an enlarged sectional view of a portion of the wall shown mFlgure 4.

' In Figure 1 is'shown a beam with ree'nforcing bars or rods at 10, the barslO bemg coated 46 at 11 throughout theiretfectlve' length with asphalt or similar. ID3116131511. The screw threaded projecting ends of the bars. 10 pass through suitable apertures in the L-shaped washers 12, and tension on the rods 10 may 50 be applied by means of nuts engaging the screw threaded ends of the rods and bearing against the washers 12.

In the lamp post shown n Flgure 2 the reperspective of a con-- I o 7 1 a lamp post with com stretch about enforce consists of a pipe 15 which may serve as a conduit for the electric light wires. It is screw-threadedat both extremities and is provided with washers "16 over the projectng extremities. The pipe 15 is surrounded by the layer 17 which preventsa bond between the reenforce and the concrete. Tension is applied to, thereenforce by means of nuts 18, one of which is shown in Figure 3. "The pipe 15"may, of'course, serve as a passageway for gas or for any other purpose, or

the pipe may be replaced b a rod. ,So far as the present application 0 the invention is concerned the part 15 is primarily a reenforce and any other function is secondary.

In Figure 3 is shown a "concrete post in which a rod 10 is positioned lengthwise and As shown in Figure 3 the coating 20 is not applied to the hook-shaped end but only to..

the reenforcing portion of the rod 19. .The projecting extremity of the rod is screwimbedded in the concrete, the rod being coated '80 threaded and is surrounded by a washer 16 s that tension may be applied by means or reenforcing rods 21 are necessarily inclined,

with the hook ends adjacent the inner or outer wall of the concrete structure. The

coating is applied throughout the effectivelength of the rod 21 at 22, but it is not applied to the hook.

It is a scientific fact well known to all concrete engineers, that the modulus of elasticity of steel is approximately 30,000,000 while that of concrete is about 3,000,000, or approximately one-tenth that of steel. The strength of steel in tGIISlOIlrlS approximately 30,000 pounds per square inch, while that of concrete is only about 300 pounds. In other oncrete Wlll stretch about 10,000

its length before cracking, and steel will ing its yield point. So that if a concrete post,

of its length before reachfins or beam, or pile, or floor, or any structure of concrete and steel that is called upon to resist a tensile strain, is stretched .of its 10,000 length the concrete will crack. If it is stretched of its length the concrete will makeshift product. My invention overcomes the (lifiiculties due to the fact that steel at rest and concrete at rest have such different capacities for elongation before rupture.

My invention permits the manufacture of a .product of concrete and steel that does not allow the concrete to break until the load reaches or exceeds the tensile strength of the steel.

However, before specifically describing my invention I desire to call attention to the fact that the means set forth in my afore mentioned application, that of stretching the steel and keeping it stretched during the setting process, as nearly to its elastic limit as is practicable, will not produce the desired result for the following reasons:

(1) Concrete, during the setting process, shrinks. The degree of shrinkage is variable. In general the richer the concrete in cement the greater the shrinkage.

(2) Concrete, after the set is apparently completed, will shrink with loss of moisture.

(3) Concrete will shrink under compression at the same rate that it will expand under tension.

Therefore, when the steel is held under tension and the plastic concrete is poured about it, what happens is this: As the concrete is initially setting it shrinks or attempts to shrink, or in other words, it is in tension. If later it dries out it will shrink some more and increase its tension, so that the product of concrete and steel will losepart or allof the tension placed in the steel and may, in addition, develop such tensional strains on the concrete as to cause the concrete to crack. In the very exceptional case where the mixture is very thin and the concrete is left moist so that it does not shrink, the tension of the steel allowed to come on the concrete will compress it so that part of its tension is lost and the product is not perfect even in that case. In reenforced concrete, as ordinarily equilibrium.

My Invention consists in :the use of relathe cracks is not at rest'but is in tension and being in tensign holds the steel in compres sion. Each section is in a state of unstable tivel smooth rods, such as the plain round reen orcmg barsof commerce, di ped or coated with a substance such as liqui asphalt that will prevent the bond of the steel to the concrete together with, subsequently to the setting and shrinking of the concrete, the ex tension of the steel bars as near their limit of tensile strength as is deemed advisable.

While liquid asphalt is mentioned as being admirably suited to the purpose described-,- many other substances or compounds may be substituted or a combination of twoor more substances may be used. I have invented the use of any substance or combination of elements that willfirst, prevent the bonding of the steel to the concrete andsecond, subsequently to the setting of the concrete, furnish sufiicient elasticity or fiow or slipperiness to permit the extension of the steel without materially harming either the steel or the concrete in which it is imbedded. I have invented the use of a substance, or combination of substances that will permit of such easy flow that the concrete in shrinking as it sets or dries will shrink along the line of the 'reenforcing without outside aid. Theuse of heat as a factor in increasing mobility or other physicalor chemical means to secure the same result is expressly included as a part of my invention.

It is obvious that this slipperiness or abil ity to permit flow, may be furnished in a number of ways. The substance used might bond itself to both the steel and the concrete and furnish the flow in its own molecular body. 01' it might bond itself to the steel and not to the concrete, but slip on the con-' crete as a base. Or, two substances might be used that bond to the steel and to the concrete respectively, but not to each other, or similar results may be obtained by any of numerous other methods. I p

Further as asubsidiary part of the main invention, and in continuance of the scientil'ic attitude in the construction of reenforced concrete, I have invented the plan of building such structures as floors of buildings, floors of bridges, concrete road ways and other types of structures now usually built as one unit, in many sections of relatively long length, as compared to the depth and width, together with the use of coated or dipped lengthwise rcenforcing. The use of the plastic coating on the reenforcing will permit shrinking of the concrbte in a lengthwise direction during or after setting. The narrow width and short depth will permit of shrinkage in these two dimensions. Each section is then a concrete product free from cracks. After the steel is placed in correct concrete in contact with each other, which v tension, the section is ready to be put in place and go into immediate sate for the lack of bond between the sections in the floor or roadway, and where a bond is desirable, I use either of these two methods: A wet grout of very rich concrete,- or of neat cement can be placed between the adjacent sections and a concrete bond thus set up. In cases where the bond is very emential I use the following method: In the construction of the sections I leave holes so placed that when the sections are put in place the holes in each section form one or more continuous holes. Through these holes I place reenforcing bars, and place them in tension. This bonds all the units together into one integral structure as far as working loads are concerned. It is obvious that the two methods may be used in combination.

As has been explained, the use of my invention permits the construction of reenforced concrete products in which the concrete is not in pieces, nor in tension in whole or in part, as is the case with reenforced concrete as usually constructed, but is free from tension or is in compression and'the steel in tension as is usually the desirable relation or where both elements are at rest. Further, the use of my invention permits the production of cracklessconcrete inthe cylindrical form for use as cisterns or ressure pipes. It is becoining generally own that a dense concrete mixture that is free from cracks is impervious to a moderate pressure of either water or air. It is obvious that the use of my invention in the production of such products is ver important.

' The ful value in saving a beam, a post, or similar structure, from failure by the use of my invention has not been fully explained.

B the use of my invention the full strength of t e steel is brought into play by a very slight distortion of the structure. If the steel is very highly tensioned, its full strength can be brought into action in support of the structure, without forming an cracks. But,in rclenforced conerese, as o "1y constfricte a comparative y ve agree 0 istortion must be accom i sh before the ten sional strength 'of the steel is developed. But, when the distortion is'great, the areasof form the bases on which the tension of the steel works as a fulcrum are v'erysmall so that the structure fails thro the crumbling of this too narrow base an as it crumbles continuall decreases the distance of the fulcrum from t e load, and thus continually increases the strain per square inch of base.

A further advantage in the use of my invention consists in the utilization of hard steel, or steel of high elastic limit and high ultimate o compen-' concrete with the reenforce em strength. It is the present practice to use steel. The distortion of a reenforccd concrete structure sufficient to develop the vfull stren of mild steel, is suflicient to complete y ruin the concrete. With the useof my invention, the required tensional strength can be obtained much more cheaply by the substitution of hard steel, sincethe strength that can be obtained by the substitution of hard steel for soft steel, increases much more ra idly than the increase in cost.

' hile the use of threads on the rod, and nuts and washers, 'will commonly be the easiest way toproduce tension with rods, I do not claim that method, nor limit myself to any specific method of producing tension.

It will also be obvious that m invention is applicable to related products, umnite cc ment as well as Portland cement, and iron or other reenforcing material as well as steel.

While I have found liquid asphalt a very satisfactory plastic non-setting substance and claim its use specifically, I do not limit myself to its use alone, but claim any substance that will do the required work as described.

Having thus described my invention in terms which will be readily understood by those skilled in the art to which it pertains, what I claim to be new and desire to secure by Letters Patent of the United States is:

1. The method of reenforcing concrete which consists in forming a bod of in, in permitting the body of-concrete to set, 1n preventing t e bonding ofthe reenforce to t e concrete during the setting of the concrete, and finally in subjecting said reenforce to tension.

2. The method of reenforcing concrete which consists in coating the reenforce with -a substance which will prevent the bonding of the concrete and the reenforce, in then forming. a body of geen concrete with the reenforce embedded erein, in permittin said body of concrete to set, and finally in 'su jecting the reenforce to tension against the resistance of the body of concrete.

3. The method of 'ree'nforcing concrete which consists in coating a reenforce with asphalt, inthen ap lying said coated reenforce to a concrete y, and finally in tensioning' said-reenforce, the arrangement bein such that the reenforce is out of bonding re ation with the concrete.

In testimony whereof I have afixed my signature.

RICHARD E. mm.

ded t ere- 

